U.S. patent application number 15/110442 was filed with the patent office on 2016-11-24 for creation of a transparent window in a security substrate for security printing applications.
The applicant listed for this patent is KBA-NOTASYS SA. Invention is credited to Aurelie BERTHON, Johannes Georg SCHAEDE.
Application Number | 20160339653 15/110442 |
Document ID | / |
Family ID | 49955957 |
Filed Date | 2016-11-24 |
United States Patent
Application |
20160339653 |
Kind Code |
A1 |
BERTHON; Aurelie ; et
al. |
November 24, 2016 |
CREATION OF A TRANSPARENT WINDOW IN A SECURITY SUBSTRATE FOR
SECURITY PRINTING APPLICATIONS
Abstract
There is described a method of creating a transparent window
(W*) in a security, especially paper, substrate (1) for security
printing applications, the method comprising the steps of (i)
providing a security substrate (1), (ii) forming an opening (10*)
into and through the security substrate (1), and (iii) filling the
opening (10*) with transparent material (2) thereby forming the
transparent window (W*). The filling of the opening (10*) with the
transparent material (2) is carried out in a state where the
opening (10*) is open on both sides of the security substrate (1)
and extends through the security substrate (1), the filling of the
opening (10*) including (10 the application of a first side (I) of
the security substrate (1) against a supporting surface (21A) of a
supporting member (20', 21) in such a way as to block one side of
the opening (10*), while the transparent material (2) is applied
inside the opening (10*) from the other side (II) of the security
substrate (1). Advantageously, the method further comprises the
step of forming a field of lenses (L) on one side of the
transparent window (W*), in particular by replicating the field of
lenses (L) directly into the transparent material (2) filling the
opening (10*). Also described is a suitable device designed to fill
the opening (10*) with the transparent material (2).
Inventors: |
BERTHON; Aurelie; (St-Prex,
CH) ; SCHAEDE; Johannes Georg; (Wurzburg,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KBA-NOTASYS SA |
Lausanne 22 |
|
CH |
|
|
Family ID: |
49955957 |
Appl. No.: |
15/110442 |
Filed: |
January 16, 2015 |
PCT Filed: |
January 16, 2015 |
PCT NO: |
PCT/IB2015/050337 |
371 Date: |
July 8, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29K 2711/12 20130101;
D21H 21/40 20130101; B29K 2711/10 20130101; B29C 70/745 20130101;
B42D 25/40 20141001; B42D 25/29 20141001; B29D 11/00298 20130101;
B29D 11/00278 20130101; B42D 25/351 20141001 |
International
Class: |
B29C 70/74 20060101
B29C070/74; B42D 25/40 20060101 B42D025/40; B42D 25/29 20060101
B42D025/29; B42D 25/351 20060101 B42D025/351; D21H 21/40 20060101
D21H021/40; B29D 11/00 20060101 B29D011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 16, 2014 |
EP |
14151506.4 |
Claims
1. A method of creating a transparent window in a security,
especially paper, substrate for security printing applications, the
method comprising the following steps: providing a security
substrate; forming an opening into and through the security
substrate; and filling the opening with transparent material
thereby forming the transparent window, wherein the filling of the
opening with the transparent material is carried out in a state
where the opening is open on both sides of the security substrate
and extends through the security substrate, the filling of the
opening including the application of a first side of the security
substrate against a supporting surface of a supporting member in
such a way as to block one side of the opening, while the
transparent material is applied inside the opening from the other
side of the security substrate.
2. The method according to claim 1, wherein the transparent
material is applied in a fluidic state inside the opening and is
subsequently solidified.
3. The method according to claim 2, wherein the transparent
material is a UV-curable fluidic material.
4. The method according to claim 2, wherein the transparent
material is applied by screen printing.
5. The method according to claim 1, wherein the filling of the
opening is carried by applying the transparent material in several
successive steps.
6. The method according to claim 5, wherein additional features,
are incorporated between at least two successive layers of the
transparent material.
7. The method according to claim 1, wherein transparent material is
applied on a portion of the supporting surface coinciding with the
location of the opening prior to application of the first side of
the security substrate against the supporting surface of the
supporting member.
8. The method according to claim 1, wherein the supporting member
includes a supporting cylinder.
9. The method according to claim 1, further comprising the step of
forming a field of lenses on one side of the transparent
window.
10. The method according to claim 9, wherein the step of forming
the field of lenses includes replicating the field of lenses
directly into the transparent material filling the opening.
11. The method according to claim 10, wherein the supporting member
includes a lens replicating medium with a lens replication
structure designed to replicate the field of lenses into the
transparent material filling the opening, which lens replicating
medium has a surface coming in contact with the first side of the
security substrate and acting as the supporting surface of the
supporting member.
12. The method according to claim 1, further including imparting a
geometry to the opening by shaping a surrounding of the opening in
order to secure adhesion of the transparent material inside the
opening.
13. The method according to claim 12, wherein the geometry imparted
to the opening is such that the opening exhibits a non-uniform
cross-section with one section, in a middle portion of the
thickness of the security substrate, that exhibits a diameter which
is less than that of sections of the opening on either side of the
security substrate.
14. The method according to claim 12, wherein the step of imparting
the geometry to the opening includes compressing the security
substrate in the area immediately surrounding the opening during or
subsequent to the formation of the opening.
15. The method according to claim 1, wherein the supporting surface
of the supporting member is provided with an anti-adhesive coating
or layer designed to prevent adhesion with the transparent
material.
16. The method according to claim 1, wherein the security substrate
is a paper substrate made e.g. of cotton fibres, a hybrid substrate
combining layers of polymer and paper material, or a composite
substrate combining polymer and paper fibres.
17. A device designed to fill an opening formed into a security
substrate with transparent material to form a transparent window in
the security substrate, which opening is open on both sides of the
security substrate and extends through the security substrate, the
device comprising: at least one supporting member with a supporting
surface against which a first side of the security substrate is
applied during a filling of the opening with the transparent
material in such a way as to block one side of the opening; and an
application system including one or more application units designed
to apply the transparent material inside the opening from the other
side of the security substrate while the first side of the security
substrate is applied against the supporting surface of the
supporting member, thereby forming the transparent window.
18. The device according to claim 17, wherein the supporting member
includes a supporting cylinder.
19. The device according to claim 17, wherein the application
system includes at least one screen-printing unit acting as
application unit and designed to apply the transparent material
directly or indirectly into the opening of the security
substrate.
20. The device according to claim 17, further comprising at least
one pressure roller located downstream of the application system
and designed to press the security substrate against the supporting
surface of the supporting member.
21. The device according to claim 17, further comprising at least
one UV curing unit designed to subject the transparent material to
a UV curing operation prior to the security substrate leaving the
supporting member.
22. The device according to claim 17, wherein the supporting member
includes a lens replicating medium designed to form a field of
lenses on one side of the transparent window, which lens
replicating medium includes a lens replication structure designed
to replicate the field of lenses into the transparent material
filling the opening, which lens replicating medium has a surface
coming in contact with the first side of the security substrate and
acting as the supporting surface of the supporting member.
23. The device according to claim 17, wherein the application
system includes at least two application units designed to apply
the transparent material in successive steps.
24. The device according to claim 23, further comprising an
intermediate UV-curing unit interposed between the at least two
application units.
25. The device according to claim 23, further comprising an
additional application unit interposed between the at least two
application units and designed to incorporate additional features,
between at least two successive layers of the transparent
material.
26. The device according to claim 17, wherein the application
system includes an application unit designed to apply part of the
transparent material onto a portion of the supporting surface
coinciding with the location of the opening prior to application of
the first side of the security substrate against the supporting
surface of the supporting member.
27. The device according to claim 17, wherein the supporting
surface of the supporting member is provided with an anti-adhesive
coating or layer designed to prevent adhesion with the transparent
material.
28. A processing machine comprising: a system designed to form an
opening into and through a security, especially paper, substrate;
and a device in accordance with claim 1 designed to fill the
opening with transparent material and thereby form a transparent
window in the security substrate.
29. A security, especially paper, substrate comprising a
transparent window formed in accordance with the method of claim
1.
30. The method according to claim 3, wherein the transparent
material is a UV-curable ink, varnish or polymer.
31. The method according to claim 6, wherein the additional
features are pigments or security elements.
Description
TECHNICAL FIELD
[0001] The present invention generally relates to the creation of a
transparent window in a security substrate (especially a security
paper substrate) for security printing applications, in particular
for the production of banknotes and like securities.
BACKGROUND OF THE INVENTION
[0002] It is known to laminate at least partially transparent films
onto one side of openings formed into and through security paper
substrates, for instance from International (PCT) Publications Nos.
WO 2008/104904 A1, WO 2009/112989 A1 and WO 201 0/001 31 7 A1 in
the name of the present Applicant (which publications are all
incorporated herein by reference in their entirety), for the
purpose of creating at least partially transparent windows in such
security paper substrates. The laminated film serves multiple
purposes, including acting as a means to close one side of the
opening that is formed into and through the substrate, as well as a
means to allow optional filling of the opening with a transparent
filling material.
[0003] The lamination of the at least partially transparent films
however necessitates a dedicated processing step which increases
production costs.
[0004] An alternate solution is therefore required with a view to
create a transparent window in a security substrate.
SUMMARY OF THE INVENTION
[0005] A general aim of the invention is therefore to provide such
an alternate solution.
[0006] More specifically, an aim of the present invention is to
provide such a solution that can suitably allow for the creation of
a transparent window in a security substrate, especially in a
security paper substrate, that does not necessitate prior
lamination of a film onto a surface of the substrate in order to
close the opening formed into and through the substrate.
[0007] These aims are achieved thanks to the solutions recited in
the claims.
[0008] In particular, there is claimed a method of creating a
transparent window in a security substrate for security printing
applications (especially a security paper substrate made e.g. of
cotton fibres), the method comprising the steps of (i) providing a
security substrate, (ii) forming an opening into and through the
security substrate, and (iii) filling the opening with transparent
material thereby forming the transparent window. According to the
invention, the filling of the opening with the transparent material
is carried out in a state where the opening is open on both sides
of the security substrate and extends through the security
substrate, the filling of the opening including the application of
a first side of the security substrate against a supporting surface
of a supporting member in such a way as to block one side of the
opening, while the transparent material is applied inside the
opening from the other side of the security substrate.
[0009] In this way, the need for lamination of a film on one side
of the security substrate, in order to close one side of the
opening prior to filling the opening, is eliminated.
[0010] There is also claimed a device designed to fill an opening
formed into a security substrate with transparent material to form
a transparent window in the security substrate, which opening is
open on both sides of the security substrate and extends through
the security substrate, the device comprising (i) at least one
supporting member with a supporting surface against which a first
side of the security substrate is applied during a filling of the
opening with the transparent material in such a way as to block one
side of the opening, and (ii) an application system including one
or more application units designed to apply the transparent
material inside the opening from the other side of the security
substrate while the first side of the security substrate is applied
against the supporting surface of the supporting member, thereby
forming the transparent window.
[0011] There is also claimed a processing machine comprising (i) a
system designed to form an opening into and through a security
substrate, and (ii) a device in accordance with the invention
designed to fill the opening with transparent material and thereby
form a transparent window in the security substrate.
[0012] Also claimed is a security substrate (especially a security
paper substrate made e.g. of cotton fibres) comprising a
transparent window formed in accordance with the method of the
invention.
[0013] Further advantageous embodiments of the invention are
discussed below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Other features and advantages of the present invention will
appear more clearly from reading the following detailed description
of embodiments of the invention which are presented solely by way
of non-restrictive examples and illustrated by the attached
drawings in which:
[0015] FIGS. 1A-E are schematic sectional views illustrating
successive steps of an embodiment of a method of creating a
transparent window in a security substrate in accordance with a
first embodiment of the invention;
[0016] FIGS. 2A-E are schematic sectional views illustrating
successive steps of an embodiment of a method of creating a
transparent window in a security substrate in accordance with a
second embodiment of the invention;
[0017] FIG. 3 is a schematic sectional view illustrating a security
substrate provided with a transparent window created in accordance
with a third embodiment of the invention;
[0018] FIG. 4 is a schematic side view of a device designed to fill
an opening formed into and through a security substrate with
transparent material in accordance with a first variant of the
invention; and
[0019] FIG. 5 is a schematic side view of a device designed to fill
an opening formed into and through a security substrate with
transparent material in accordance with a second variant of the
invention.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0020] The present invention will be described in the particular
context of the creation of transparent windows in security
substrates which are provided in the form of successive sheets, the
security substrates being provided with an opening which is formed
into and through the substrate. The invention is however equally
applicable to the processing of a security substrate in the form of
a continuous web. The security substrate is typically a security
paper substrate made of e.g. cotton fibres as conventionally used
in banknote printing applications. The instant invention is however
not limited to security paper substrates only and may be applied to
the processing of any other suitable substrate material, including
so-called hybrid substrates combining layers of polymer and paper
material or composite substrates combining polymer and paper
fibres. The instant invention is actually applicable to the
processing of any type of substrate which is normally substantially
opaque and within which one desires to create one or more
transparent windows.
[0021] The expression "transparent window(s)" shall be understood
as designating any opening formed into a security substrate and
filled with a transparent material so as to exhibit, at least in
part, transparent portions allowing an observer to see through the
substrate. As this will be appreciated, features may be added to
the transparent filling material and/or provided on one surface
and/or the other of the transparent window so as to take advantage
of the transparent properties of the window.
[0022] As such, the formation of openings into and through security
substrates, in particular by punching or cutting a hole (for
instance by laser cutting) into security paper sheets is known in
the art. As already mentioned, the formation of such openings is
usually followed by the lamination of a transparent film onto a
first side of the security substrate so as to close on end of the
opening, as for instance disclosed in International (PCT)
Publications Nos. WO 2008/104904 A1, WO 2009/112989 A1 and WO 201
0/001 31 7 A1 in the name of the present Applicant, which
publications are all incorporated herein by reference in their
entirety. Filling material can subsequently be applied inside the
opening as for instance disclosed in International (PCT)
Publications Nos. WO 2005/116335 A1 and WO 2010/000432 A1, which
are also incorporated herein by reference in their entirety. The
invention differs from this known approach in that no film is
applied on the surface of the security substrate in the region of
the opening, prior to filling the opening.
[0023] This process is schematically illustrated by FIGS. 1A-E,
2A-E and 3 in reference to distinct illustrative embodiments of the
invention.
[0024] In accordance with a first embodiment of the invention as
illustrated by FIGS. 1A-E, the security paper substrate 1 is first
provided with an opening 10, namely a through-hole. This can be
performed by punching or cutting a hole through the thickness of
the security substrate 1 (for instance by means of a suitable
mechanical cutting tool or by means of a laser beam).
[0025] According to this first embodiment, and prior to filling the
opening 10 with transparent material in order to form the desired
transparent window, a first side I of the security substrate 1 is
applied against a supporting surface 20A of an adequate supporting
member 20 (see FIG. 1C) in such a way as to block one side of the
opening 10, i.e. on the first side I of the security substrate 1.
The substrate 1 remains in this state, while transparent material 2
is applied inside the opening 10 from the other (second) side II of
the security substrate 1 (see FIG. 1D).
[0026] The supporting surface 20A may advantageously be provided
with an anti-adhesive coating or layer designed to prevent adhesion
with the transparent material 2.
[0027] The transparent material 2 is conveniently applied in a
fluidic state inside the opening 10 and is subsequently solidified.
This can in particular be done through the use of a UV-curable
fluidic material, such as a UV-curable ink, varnish or polymer. In
that context, the application of the UV-curable transparent
material 2 is followed by a UV-curing operation in order to
initiate reticulation, and therefore solidification of the
transparent material 2.
[0028] Application of the transparent filling material 2 can be
performed by any suitable process. A preferred method is to apply
the transparent filling material 2 by screen printing.
[0029] The filling of the opening 10 can be carried out in a single
step or, should this be required or more convenient, is several
successive steps. In the latter case, subsequent layers of
transparent material 2 could be applied one after the other inside
the opening 10 and one could even contemplate to incorporate
additional features (such as pigments or security elements) between
two successive layers of transparent material 2, thereby embedding
such features within the thickness of the transparent window W
itself.
[0030] The resulting substrate 1, with its transparent window W, as
schematically illustrated in FIG. 1 E, could be further processed.
For instance, a field of lenses (not shown) could be provided on
one or the other side of the transparent window W, while the
opposite side of the window W could be provided with a
corresponding image pattern, coordinated with the field of lenses
so as to create variable optical effects depending on the viewing
angle, when viewed through the field of lenses. Such field of
lenses could as a matter of fact be formed at the same time as the
opening is filled with transparent material, as discussed in
reference to the embodiment of FIGS. 2A-E and 3, or, alternatively,
subsequently to the formation of the transparent window W, for
instance by applying a layer of material in which the field of
lenses is replicated or by applying a film of material already
comprising the field of lenses.
[0031] FIGS. 2A-E illustrate a second embodiment of the invention
wherein the security substrate 1 is provided with an opening 10*
extending through the substrate 1 and exhibiting a geometry that is
imparted to the opening 10* by shaping a surrounding thereof in
order to secure adhesion of the transparent material inside the
opening 10*. More precisely, the opening 10* exhibits a non-uniform
cross-section with one section, in a middle portion of the
thickness of the security substrate 1 (i.e. where the distance
between opposing flanks of the opening 10* is the shortest), that
exhibits a diameter which is less than that of sections of the
opening 10* on either side I, II of the security substrate 1. This
particular geometry ensures that the transparent filling material 2
is adequately secured to the opening 10* and can be imparted by
shaping the surrounding of the opening 10*, during or subsequent to
the formation of the opening 10*, in particular by compressing the
security substrate 1 in the area immediately surrounding the
opening 10*.
[0032] In contrast to the first embodiment, the first side I of the
security substrate 1 is applied against a supporting surface 21A of
a supporting member 20', 21 which includes a lens replicating
medium 21 having a lens replicating structure 21B that is located
on the supporting surface 21A (see FIG. 2C) so as to coincide with
the position of the opening 10*. One side of the opening 10* is
likewise blocked as a result, while transparent material 2 is
applied inside the opening 10* from the second side II of the
security substrate 1 (see FIG. 2D).
[0033] The supporting surface 21A may likewise advantageously be
provided with an anti-adhesive coating or layer designed to prevent
adhesion with the transparent material 2.
[0034] Part of the transparent material 2 could be applied directly
onto a portion of the supporting surface 21A, in particular in
order to pre-fill the lens replicating structure 21B prior to
pressing the first side I of the security substrate 1 against the
supporting surface 21A of the supporting member 20', 21. This
improves the filling of the opening 10* and ensures that all
relevant portions of the opening 10* are appropriately filled with
transparent material 2. This further ensures optimum replication of
the desired field of lenses L.
[0035] This approach could also be applied in the context of the
first embodiment of FIGS. 1A-E, even though no lenses are
replicated, by similarly applying transparent material 2 to a
portion of the supporting surface 20A coinciding with the opening
10, prior to application of the first side I of the security
substrate 1 against the supporting surface 20A of the supporting
member 20.
[0036] Like in the first embodiment, the transparent material 2 is
preferably a UV-curable material that is applied in a fluidic
state, and then solidified by UV-curing. In this other embodiment,
the transparent polymer material 2 is likewise preferably cured by
UV radiation from the second side II of the security substrate 1,
while the security substrate 1 is in contact with the supporting
surface 21A of the supporting member 20', 21.
[0037] The resulting substrate 1 with its window W* provided on one
side with a field of lenses L is schematically depicted in FIG. 2E.
The lenses L preferably have a lens pitch P.sub.L of the order of
10 to 50 .mu.m and a lens height h.sub.L of the order of 10 to 20
.mu.m. In comparison, the overall thickness of the security paper
substrate is of the order of 60 to 120 .mu.m.
[0038] FIG. 3 shows a security substrate 1 provided with a
transparent window W** created in accordance with a third
embodiment of the invention. This embodiment differs from the
embodiment illustrated in FIG. 2E in that the surrounding of the
opening 10** is shaped differently, but with a view to achieve a
similar objective, namely securing adhesion of the transparent
material 2 inside the opening 10**. As illustrated, the window W**
is likewise provided with a field of lenses L that is
advantageously replicated directly into the transparent material 2
filling the opening 10**.
[0039] As a result of the filling of the openings 10, 10*, 10**
with the transparent polymer material 2, there is formed a
transparent polymer window W, W*, W** in the security substrate
which exhibits a thickness in the order of magnitude of the
thickness of the security substrate 1. The security substrate 1
thus provided with the transparent polymer window W, W*, W** can
suitably be printed on the first side I and/or second side II with
patterns. In the context of the embodiment of FIGS. 2A-E and 3, the
second side II of the security substrate 1 can in particular be
printed in the region of the transparent window W*, W**, in
register with the lenses L, so as to interact with the lenses L and
form an optically-variable security feature that is observable
through the window W*, W** and lenses L, from the first side I of
the security substrate 1.
[0040] As this will be appreciated hereinafter, the transparent
material 2 is preferably applied by screen-printing using one or
more screen-printing units as application unit(s). More than one
application units may be necessary in order to suitably apply
transparent material 2 in a quantity sufficient to fill the opening
10, 10*, 10**.
[0041] FIG. 4 is illustrative of a first variant of a device
designed to fill the opening 10 formed into the security substrate
1 with transparent material 2 in accordance with the methodology
that was previously described in reference to FIGS. 1A-E. The
device of FIG. 4 is in particular designed to process security
substrates 1 in the form of individual sheets that are transported
one after the other in succession and that have already been
provided with the desired openings 10. The formation of the
openings 10 can be carried out in an in-line process upstream of
the depicted device of FIG. 4.
[0042] In the context of FIG. 4, the security substrate 1 is
transferred to a supporting cylinder 20 (which also acts as
transport cylinder in this illustrative example) by means of
transfer cylinder 18. This supporting cylinder 20 acts as
supporting member for the first side I of the security substrate 1,
with a circumference 20A of the supporting cylinder 20 acting as
the supporting surface against which the first side I of the
security substrate 1 is pressed. An application system A is
provided, which comprises an application unit 14 designed to
cooperate with the supporting cylinder 20 and the second side II of
the security substrate 1 in order to apply the transparent material
2 in the opening 10 formed in the security substrate 1. This
application unit 14 is preferably designed as a screen-printing
unit. A suitable screen-printing unit is for instance disclosed in
European Patent Publication No. EP 0 723 864 A1 in the name of the
present Applicant, which is incorporated herein by reference in its
entirety.
[0043] Downstream of the application unit 14, there is preferably
provided a pressure roller 30 which is designed to press the
security substrate 1 from the second side II, thereby ensuring
proper penetration of the transparent material 2 into the openings
10. Additional pressure rollers may be provided in order to ensure
optimum application of the security substrate against the
circumference 20A of the supporting cylinder 20. A surface of the
pressure roller(s) 30 could advantageously be structured to come
into contact only with portions of the security substrate 1 outside
of the regions of the openings where the transparent material is
applied.
[0044] The device further comprises a UV-curing unit 50 cooperating
with the supporting cylinder 20 in order to cure the UV-curable
material 2 from the second side II of the security substrate 1,
while the security substrate 1 is in contact with the supporting
surface 20A of the supporting cylinder 20. Subsequent to the
UV-curing operation, the security substrate 1 is taken away from
the supporting cylinder 20 and transferred to a transfer cylinder
22 for delivery or further processing.
[0045] FIG. 5 is illustrative of a second variant of a device
designed to fill the opening 10*, respectively 10**, formed into
the security substrate 1 with transparent material 2 in accordance
with the methodology that was previously described in reference to
FIGS. 2A-E and 3. This other variant differs from that of FIG. 4 in
various aspects. Firstly, the supporting member is designed in this
variant as a supporting cylinder 20' carrying a lens replicating
medium 21 (as described above), the surface 21A of the lens
replicating medium 21 acting as the supporting surface. Secondly,
two application units 14', 14'' (which are likewise preferably
constructed as screen-printing units) cooperate with the supporting
cylinder 20' and the lens replicating medium 21. In addition, a
further application unit 24 (similarly preferably constructed as a
screen-printing unit) is located upstream of the transfer cylinder
18 so as to apply transparent material 2 onto a portion of the
surface 21A of the lens replicating medium 21 (where the lens
replicating structure 21B is located) prior to transfer of the
security substrate 1 to the supporting cylinder 20' by the transfer
cylinder 18.
[0046] Various modifications and/or improvements may be made to the
above-described embodiments without departing from the scope of the
invention as defined by the annexed claims. For instance, in the
illustrative example of FIG. 5, an intermediate UV-curing unit may
be provided between the two application units 14', 14'' in order to
initiate curing of the transparent material 2 applied by the first
application unit 14'. In addition, as already mentioned, one or
more application units may be interposed between the two
application units 14', 14'' in order to incorporate additional
features (such as pigments or security elements) between two
successive layers of transparent material 2, thereby effectively
embedding such features within the thickness of the transparent
window itself.
LIST OF REFERENCE NUMERALS USED THEREIN
[0047] 1 security substrate (especially security paper substrate
made e.g. of cotton fibres)
[0048] I first side of the security substrate 1
[0049] II second side of the security substrate 1, opposite to the
first side I
[0050] W, W*, W** transparent window formed in the security
substrate 1
[0051] L field of lenses formed onto the surface of the window W*,
W** in register with the opening 10*, 10** (FIGS. 2A-2E, 3)
[0052] P.sub.L lens pitch (spacing between adjacent
lenses--preferably in the range of 10 to 50 .mu.m)
[0053] h.sub.L lens height (preferably in the range of 10 to 20
.mu.m) transparent material (in particular UV-curable material)
used to fill the opening 10, 10* formed into and through the
security substrate 1
[0054] 10, 10*, 10** opening (through-hole) formed into the
thickness of the security substrate 1
[0055] A, A' application system for applying the transparent
material 2
[0056] 14, 14', 14'' application unit(s), in particular
screen-printing unit(s) designed to apply (at least part of) the
transparent material from the second side II of the security
substrate 1
[0057] 18 transfer cylinder (upstream side) cooperating with the
supporting cylinder 20, 20'
[0058] 20 supporting cylinder (support member) cooperating with the
application unit 14 and supporting the first side I of the security
substrate 1
[0059] 20A supporting surface of the supporting cylinder (support
member) 20 in contact with the first side I of the security
substrate 1
[0060] 20' supporting cylinder cooperating with the application
units 14', 14'' (and 24) and supporting the first side I of the
security substrate 1
[0061] 21 lens replicating medium carried by the supporting
cylinder 20' (jointly acting as supporting member with the
supporting cylinder 20') designed to form the field of lenses L
onto the surface of the window W*, W** and to support the first
side I of the security substrate 1 via the lens replicating medium
21 (FIGS. 2C, 2D, 5)
[0062] 21A supporting surface of the lens replicating medium 21
carried by the supporting cylinder 20' in contact with the first
side I of the security substrate 1
[0063] 21B lens replicating structure of the lens replicating
medium 21
[0064] 22 transfer cylinder (downstream side) cooperating with the
supporting cylinder 20, 20'
[0065] 24 additional application unit, in particular
screen-printing unit, designed to apply part of the transparent
material from the first side I of the security substrate 1
[0066] 30 pressure roller cooperating with the second side (II) of
the security substrate 1 and pressing the security substrate 1
against the supporting surface 20A, 21A
[0067] 50 UV-curing unit cooperating with the supporting cylinder
20, 20' to cure the transparent (UV-curable) material 2 from the
second side II of the security substrate 1
* * * * *